GIVE DA TREAT!

Anyway, I also have a few training questions..now like I said, he is doing well with the whistle recall I'm doing. I've only been doing it for three days, but it seems that he's only listening for treats to me..but then again when I trained with Sassy she was the same way but eventually listened to me w/o treats. I just don't want him to think he's gonna be getting treats ALL the time after he's done with this training. And sometimes, even when he knows there aren't treats..he walks away but he will usually come when I blow the whistle. I'm just worried because sometimes he'll follow me because he KNOWS I have treats which is of course exactly what I want him to do, but I just want to be careful. Thanks for any tips!